Vitiligo is an autoimmune disease caused by T-lymphocyte-mediated destruction of melanocytes. We describe two patients with generalized vitiligo caused iatrogenically after donor lymphocyte infusion (DLI) for leukaemia relapse over 3 years after bone marrow transplantation (BMT). Neither the sibling donor nor the recipient had vitiligo or other autoimmune diseases, and vitiligo did not occur after the first BMT. DLI was accompanied by skin graft-versus-host disease in both cases, which was controlled with immunosuppression. However, over several months, progressive generalized and persistent skin depigmentation occurred in both patients. Peripheral blood molecular studies showed the complete disappearance of host haematolymphopoiesis. The specific destruction of melanocytes in both patients was therefore probably mediated by new alloreactive lymphocytes infused from the donors.